The present invention relates to seed planting assemblies in general, and in particular relates to a method and apparatus for selectively disengaging seed planting units of a seed planting assembly.
Seed planting units generally include a laterally extending tool bar that supports a plurality of parallel planting units (also known as row units). The tool bar is typically coupled to a tractor or like vehicle suitable for towing the planting assembly along a field that is to be cultivated. Each planting unit includes a device for opening a seed trench in the ground as the tractor draws the tool bar across a field to be seeded. Each planting unit further includes a seed meter to dispense seeds at a controlled rate into a seed trench as the meter is advanced above and along the seed trench during operation. One such seed metering assembly is described in U.S. Pat. No. 6,401,638 assigned to Case Corp., Racine, Wis., the disclosure of which is hereby incorporated by reference for the purpose of general background information. Generally, seeds are delivered to the metering assembly from a seed hopper located on the planting unit or, alternatively, from a smaller container fed from a centralized large hopper used to feed all or a portion of the planting units. Each planting unit further includes a closing assembly that moves soil at the sides of the seed trench to close the seed trench over the planted seeds. Adjacent planting units are laterally spaced a sufficient distance to form seed trenches that are spaced a corresponding distance apart that is suitable for the type of seed being planted.
Air pressure differential seed meters, which are commonly known as air seed meters, are generally of two types, the first being a positive pressure type meter, and the second relying upon negative pressure or a vacuum. A positive pressure air seed metering mechanism includes a rotating disc defining apertures extending therethrough that are sized to retain one or more seeds to be planted. The metering mechanism is connected to an air mover that blows air into the seed chamber and onto the surface of the disc. The high pressure caused by the air mover creates a high pressure in the chamber that forces seeds from a seed mass into the apertures where they are retained for subsequent release into the seed trench as the seed member rotates. Vacuum seed meters typically include a vacuum source coupled to a separate chamber on the opposite side of the seed disc from the seed mass in the metering assembly. The vacuum pressure communicates through the disc apertures, and is sufficiently strong to draw the seed mass into the seed disc apertures. The seeds are held in the apertures until the disc rotates the seeds to the seed discharge area of the metering mechanism.
During a planting operation, the desired spacing between adjacent seed trenches can vary depending upon the type of seed being planted. In a typical arrangement, all thirty-one planting units are spaced along the toolbar at a sufficient distance to accommodate seeds that can be planted in narrowly spaced adjacent seed trenches to maximize the crop yield. Examples of such seeds include soybeans. Other types of seeds, such as corn, require that the distance between adjacent seed trenches be increased. The increased distance is typically accomplished by disengaging every other seed planting unit, thereby doubling the lateral distance between adjacent seed trenches that are created during operation.
Seed planting units are conventionally disengaged by removing the corresponding metering assemblies from the air mover source and, if necessary, operatively disconnecting the metering assembly from the seed hopper. Next, seed planting units can be selectively raised by rotating each unit about the tool bar and above ground level to prevent the planting unit from forming a seed trench. A locking mechanism is present to retain the planting unit in its raised position. Unfortunately, planting units typically weigh hundreds of pounds, making it difficult, if not impossible, to manually lift each unit to its raised position. Mechanical lifts are therefore sometimes employed, whose operation can be cumbersome and time consuming, especially when lifting up to fifteen planting units in a given seed planting assembly.
What is therefore needed is a method and apparatus for selectively raising and locking a planting unit in a more time efficient and less labor-intensive manner than conventionally achieved, and to further increase the reliability of such a method and apparatus.